Meal Replacement Shakes for Weight Loss…Do They Work?

There are a lot of products on the market that claim to help you lose weight, including protein shakes, meal replacement bars, supplements and teas.  Do these things really help you lose weight?

Meal Replacement Shakes for Weight Loss

There has been a lot or research published on using meal replacements during weight loss and the research has been pretty compelling.

In today’s post, we’ll tell you just how effective they are, why they are effective, and some little known secrets for supercharging the fat loss potential of this powerful tool.

Go On a Diet Or Add Two Meal Replacements…Your Choice

According to the research, using meal replacements could result in an equal amount of weight loss compared to structured dieting…

According to one Australian study, a group of overweight/obese subjects were either instructed to replace two meals with a can of SlimFast (which we consider a mediocre product) or were given food vouchers and detailed instructions for eating a low fat/low-calorie diet.

At the end of the study, both groups had lost about the same amount of weight over a 6 month period (~ 9 kgs, equal to approximately 20 pounds).1

Meal Replacements Helps More People Stick To The Program

In the Australian study, the folks who replaced their meals with shakes had an easier time sticking to the program than the structured-diet group. This benefit was also seen in other studies as well!

In a British study, women who were given meal replacements enjoyed similar weight loss than those who were placed on a standard low-calorie diet. What was interesting was that more women in the meal replacement group responded to the intervention than in the diet only group.2

It appears that convenience is a key advantage of replacement shakes! It seems like common sense, but I can tell you that common sense does not always win out in the weight loss research…in this case, however, it does! Convenience matters…

Meal Replacement Shakes Help You Keep It Off

One study from the U.S. Army found that soldiers who were randomized to meal replacements versus diet counseling alone, lost 2.6 more pounds of weight and 1.6 more pounds of fat. What was interesting was that this intervention was meant to help the subjects maintain weight loss, rather than to produce weight loss.3

It bares mentioning that other research has confirmed that 1-2 meal replacement shakes can help you to maintain your fat loss after your weight loss goals have been met.

Why Meal Replacement Shakes Work…

People have difficulty losing weight for one of two reasons, either they’re eating too many calories or they’re eating too few calories.

I’ll point out that I do not ascribe to a calorie-counting model of weight loss, it’s my opinion that calorie intake is regulated by hormones and the proper way to burn fat is to correct the hormonal imbalances in the body so that the subconscious areas of the brain will control caloric intake with little conscious effort on your part.

For more information on why the “Calories In, Calories Out” model of weight loss is insufficient, check out the podcast Episode 56: Exterminating the Calorie-Myth of Weight Loss With Jonathan Bailor of The Smarter Science of Slim. For now, let’s just say that you’re either eating too many calories or too few calories…different ends of the spectrum, the same result…stalled fat loss or fat gain.

If You Eat Too Much…

Most of these products are designed to help you reduce your calorie intake by offering a convenient alternative to higher calorie meals and snacks.  For example: If a typical meal for you contains 500 calories and you replace two of those meals each day with a protein bar or diet shake that contains 200 calories each, you’ve cut 600 calories from your diet without much effort or deprivation.  That could certainly help you burn fat, but only if you are eating a lot of extra calories.

Meal replacement shakes are also extremely convenient. Often times, convenience means the difference between fat loss success and failure. When you have a craving for chocolate, if you have a chocolate protein shake handy, then you may be able to scratch that dietary itch without the negative consequence of excess calories or carbs.

Quality Shakes Can Shift The Carb-Protein Balance…

Meal replacement shakes can help you to replace a normal high-carb, high-fat meal with a higher-protein alternative, which can swing the macro-nutrient balance in favor of fat loss.

By replacing that high-carb/high-fat meal with a protein shake, you may significantly decrease the total amount of insulin that your body produces in a day and the total amount of glucose that your liver has to process. These two factors are almost guaranteed to result in less fat storage.

By shifting the macro-nutrient balance in favor of less glucose and less insulin, you will better balance various hormones that will impact fat storage, metabolism, and appetite.

If You Eat Too Few Calories…

If you fall into the camp that is constantly starving themselves by dieting, then adding a protein shake on top of the calories that you consume may help to protect the muscle, lower hunger hormones, and stoke metabolism.

If you’re eating too few calories, the trick is to use these shakes as an additional snack, rather than a replacement for food.

The Secrets to Supercharging Your Meal Replacement Shake for Weight Loss…

Clearly meal replacements can play an important role in your weight loss lifestyle and they can even mean the difference between success and failure for many people, but they only work if you know one important secret, without this first secret, I feel that this valuable tool will be a total and utter failure…

In order for you to use meal replacement shakes successfully; you must use them as support for a REAL FOOD DIET!

If you expect to live off of a diet of bars and shakes, it may work for a while, but eventually your body will catch on and weight loss will cease. Soon, cravings will take over and the replacement supplements will be rendered totally ineffective.

Real food, meaning fruits, vegetables, nuts, meat, eggs, etc., are complex nutrition-rich foods full of vitamins, mineral, fiber, phytochemicals, fats, proteins, and yet to be discovered compounds that likely have a positive impact on our health, wellness and fat loss efforts.

Bottom line: Your body knows when you’re eating real food and when you’re consuming fake foods (even protein shakes)…it NEEDS real nutrition first. Only then will you get the most benefit from your meal replacements!

Watch Your Fiber!

Fiber is critical for fat loss, in practically every study to date, more fiber intake resulted in more fat loss.

In the research, those people who were given the meal replacement shakes had a tendency to consume less fiber throughout the day.1 You can counter this issue simply by eating more low-glycemic fruits, vegetables, and nuts during your REAL-FOOD meals.

You can add fiber to the meal replacement shakes, which will give you bonus points, but try to get the majority of your fiber from real foods rather than from supplements.

Avoid “Loaded” Meal Replacement Shakes

Many of these meal replacement products are loaded with chemicals, preservatives and artificial sweeteners, which can hinder your weight loss over the long term.

Choose shakes that have fewer than 10 grams of carbs and no more than 5 grams of sugar (less if possible). Look for meal replacement shakes that use stevia, xylitor, lohan fruit, or erythritol as a sweetener. These sweeteners are more natural and won’t negatively impact your blood sugar.

The Best Meal Replacement Is…Wait For It…Wait For It…

All this being said, remember, the best meal replacement is real food. Think about it…

The goal of using meal replacements is to consume fewer calories and to regulate the amount of carbohydrates and unhealthy fats. When you eat real food (i.e. fruits, vegetables, lean meats, fish, poultry, eggs, etc.), you’re almost always consuming fewer calories than what you would get out of a refined food!

Focus on eating real food.  Not processed, chemical-laden so-called “food” – but real, honest-to-goodness food straight from nature.

It has been proven time and time again that the healthiest diet on the planet is comprised of wholesome, natural foods like vegetables, fruit, nuts, seeds, and lean protein.  These foods have been altered very little from their original form, and therefore contain the most nutrients possible.

A Huge Secret For Those Who Are Always Hungry…

Remember this…real foods get registered!

One of the biggest problems with refined diets is that the concentrated, nutrient-poor foods inhibit the body’s ability to register calories!

Your brain has a calorie thermostat that shuts off appetite once you’ve eaten enough to meet the body’s needs.

Let’s say for example that your body’s thermostat is set to 500 calories in a meal. Once you have eaten 500 calories of real food, the brain sends out signals to stop eating…we call these “satiety signals”.

If, however, you drink 300 calories of soda before your meal even gets to the table, research has shown that those calories fly right under the radar of your calorie thermostat. In other words, you will eat your 500 calories ON TOP of the 300 calories from soda that you already consumed!

Meal replacements can work when eaten as a snack or meal replacement as long as your body feels that you are getting enough real food throughout the rest of the day.

When you cut out excessive sugar, sodium, processed fats and other refined foods, your body functions much more efficiently and you automatically start losing weight.  Real foods are lower in calories, bulkier (thus more filling) and contain far more nutrients than most manufactured weight loss products.

By building a foundation of eating real food, you give your body the best possible chance to return to a healthy weight and stay there – and it will usually happen much faster than it would by relying on dietary aids.

Don’t get me wrong, I use protein shakes, bars, and other supplements, but ONLY on top of a diet made up of mostly REAL food! The protein shakes and bars simply help me get my protein, calories, and snack-fixes in, especially when I am busy or on the run!

How Often Should I Use a Meal Replacement Shake?

Researchers have found that you can replace up to 3 meals with shakes for weight loss purposes, however, my opinion differs slightly…

If you are taking my advice and eating real food for the majority of the day, you should need no more than one to two shakes per day.

Researchers found that replacing a single meal with a meal replacement shake (in this case lunch) resulted in weight loss and no compensatory eating (i.e. subconsciously eating more food to make up for the missing calories).

During the course of this study, participants ended up easily maintaining a deficit of 250 calories despite having access to a buffet each day, they achieved this goal simply by consuming a protein shake in place of lunch.4

I’m a minimalist when it comes to using meal replacement shakes, that is, if you want to use them at all, I would recommend replacing one meal with a protein shake or smoothie, and testing to see how you respond. If need be, increase to two meal replacements per day. I never recommend more than two. If you believe that you need more than one or two shakes, then you’re not likely eating enough real food.

For maintenance, one shake should do it.

A Few More Tips:

  • If you exercise, and I assume that you do, then you could use a protein shake as a post-workout snack. Exercise, especially resistance training, increases the protein needs and having a post-exercise, protein snack, can actually trigger more muscle growth. It is important to have the protein within 1 hour of finishing your workout.
  • If you suffer with diabetes, you may want to start your morning with a low-carb, protein shake. For diabetics, skipping carbs at breakfast could provide a more balanced blood sugar throughout the day, even if it means consuming more carbs with lunch and dinner.
  • Some people like to use liquid protein snacks while juicing or during a fast. If you are fasting, then you may want to use a clean protein powder as a source of additional amino acids  to avoid muscle loss.
  • Protein powders may be a good alternative to higher carbohydrate liquids such as milk and juice. Whenever possible, crowd out these high calorie, high-carb liquids while using the supplements to minimize snacking on refined foodstuffs.


  1. J Nutr. 2004 Aug;134(8):1894-9.
  2. Nutr Metab (Lond). 2011 Sep 22;8(1):64.
  3. Journal of the American Dietetics Association, 110;268-273,2010.
  4. Appetite. 2011 Oct;57(2):311-7. Epub 2011 May 11
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